Innovative prestressed scaffolding system

Abstract

Disclosed herein is a support system that is temporarily placed below ground for preventing collapse of the excavated ground when a subway is constructed or a basement of a building is built. The excavated ground or load is supported by means of supporting members, the supporting members being pre-stressed by means of tensioning members and tendon support members serving to support the tensioning members. Consequently, the number of struts for supporting vertical piles and wales is considerably reduced so that obstacles in the under-ground space when it is excavated are removed. Furthermore, the constructional efficiency of the underground space is greatly improved, and the cost of construction is sharply reduced.

1. A pre-stressed support system for supporting the excavated ground load by using supporting members, a tendon support member being arranged about the central region of said supporting members along a longitudinal direction of said support members, a plurality of tendon support members each height being gradually decreased from the center of said supporting members toward both directions thereof and each being disposed at a predetermined interval, and tensioning members being fixedly supported on said plurality of tendon support members to thereby form an overall semi-parabola shape. 
   
   
     2. The system as defined in  claim 1 , wherein said supporting members are horizontal beams such as wale for supporting the excavated ground. 
   
   
     3. The system as defined in  claim 1 , wherein said supporting members are vertical piles for supporting the excavated ground. 
   
   
     4. The system as defined in  claim 1 , wherein said supporting members are main girder for withstanding load. 
   
   
     5. The system as defined in  claim 1 , wherein said supporting members are H-piles, steel piles having circular or square sections, or concrete piles having circular or square sections. 
   
   
     6. The system as defined in  claim 1 , wherein said tensioning members are selected from a group consisting of tendons, carbon fibers, glass fibers, aramid fibers, and etc. 
   
   
     7. The system as defined in  claim 3 , wherein said tendon support members and said tensioning members are attached to said supporting members so that said supporting members are pre-stressed at the upper and lower parts thereof in the longitudinal direction, and struts for supporting said supporting members are further provided. 
   
   
     8. The system as defined in  claim 3 , wherein said tendon support members and said tensioning members are attached to said supporting members so that said supporting members are pre-stressed at the lower part thereof in the longitudinal direction, and said supporting members are disposed at both sides of the excavated underground space in the lateral direction and longitudinal direction in large numbers, and said tendon support members and said tensioning members are attached to main girders so that they are pre-stressed and, said main girders are attached to the upper ends of said supporting members disposed at both sides of the excavated underground space so that cover plates are placed on said main girders, a main structure is built in the space between said supporting members disposed at both sides of the excavated underground space at the lower parts of said supporting members, and struts are placed on the main structure such that said struts are fixed to said supporting members disposed at both sides of the excavated underground space. 
   
   
     9. The system as defined in  claim 1 , wherein said supporting members are wales disposed at both sides of the excavated underground space in the longitudinal direction, said tendon support members comprise two of first tendon supports disposed at the middle part of each of said wales in the longitudinal direction and second tendon supports attached to said wales at both sides of said first tendon supports such that the height of said second tendon supports are lower than that of said first tendon supports, said tensioning members are placed on said tendon support members so that said wales are pre-stressed, said struts are disposed at regular intervals in the longitudinal direction of said wales in pairs such that said struts are attached to said wales, the pairs of said struts being braced. 
   
   
     10. The system as defined in  claim 9 , wherein a plurality of vertical piles extended in the vertical direction of the excavated underground space are disposed at said wales at regular intervals, said tendon support members and said tensioning members are respectively attached to said vertical piles so as to be pre-stressed at a region directly subjected to the earth pressure in the longitudinal direction. 
   
   
     11. The system as defined in  claim 1 , wherein said supporting members comprise a plurality of first vertical piles arranged at regular intervals in the longitudinal direction and extended in the vertical direction of the excavated underground space, and second vertical piles disposed at both sides of the excavated underground space and extended in the vertical direction of the excavated underground space;
 said tendon support members and said tensioning members are disposed at the lower parts of said first and second vertical piles so that the lower parts of said first and second vertical piles are pre-stressed; 
 a plurality of wales are disposed at the upper and lower parts of said first vertical piles so that said first vertical piles are attached to said wales; 
 said tendon support members and said tensioning members are disposed at said wales so that said wales are pre-stressed; 
 the upper ends of said second vertical piles disposed at both sides of the excavated underground space are connected to each other by means of main girders; 
 cover plates are placed on said main girders; 
 said tendon support members and said tensioning members are disposed at said wales so that said wales are pre-stressed; 
 said second vertical piles disposed at both sides of the excavated underground space are connected to each other by means of a plurality of struts; and 
 the main structure is built in the space between said first and second vertical piles. 
 
   
   
     12. The system as defined in  claim 1 , comprising the steps of:
 disposing vertical piles at both sides of the excavated underground space in the longitudinal direction after the ground is excavated to a prescribed depth; 
 pre-stressing main girders by means of tendon support members and tensioning members; 
 disposing the main girders at the upper ends of said vertical piles disposed at both sides of the excavated underground space such that said main girders are connected to said vertical piles; 
 pre-stressing wales by means of tendon support members and tensioning members; 
 disposing said wales at said vertical piles such that said wales are connected to said vertical piles arranged in the longitudinal direction; 
 fixing struts to the lower parts of said vertical piles; and 
 pre-stressing the lower parts of said vertical piles by means of tendon support members and tensioning members. 
 
   
   
     13. The system as defined in  claim 1 , wherein said tendon support members are trusses fixed to said supporting members in the longitudinal direction so that said tensioning members are laid on the trusses while said tensioning members are supported by means of said trusses. 
   
   
     14. The system as defined in  claim 13 , wherein each of the trusses has a long side, a 
     short side, and first and second oblique sides connecting the long and short sides, the long and short sides and the first and second oblique sides together forming a trapezoidal shape, so that one end of said tensioning member is fixed to one surface of the long side of said truss, passes through the first oblique side and the short side of said truss, and is fixed to the other surface of the long side of said truss via the second oblique side of said truss. 
   
   
     15. The system as defined in  claim 13 , wherein each said trusses has a long side, a short side, and first and second oblique sides connecting the long and short sides, the long and short sides and the first and second oblique sides together forming a trapezoidal shape, so that one end of said tensioning member is fixed to one surface of the long side of said truss, is extended to the middle part of the short side of said truss and fixed to the short side, and is fixed to the other surface of the long side of said truss. 
   
   
     16. The system as defined in  claim 13 , wherein each of said trusses has a long side, a short side, and first and second oblique sides connecting the long and short sides, the long and short sides and the first and second oblique sides together forming a trapezoidal shape, so that one end of said tensioning member is fixed to one surface of the short side of said truss, is extended in the longitudinal direction of the short side of said truss, and is fixed to the other surface of the short side of said truss. 
   
   
     17. The system as defined in  claim 1 , wherein both ends of said respective tensioning members are fixed by means of anchoring units attached to said supporting members. 
   
   
     18. The system as defined in  claim 1 , wherein each of said tendon supports has a tendon base formed at the upper end thereof, said tendon base having a curved tendon guide. 
   
   
     19. The system as defined in  claim 1 , wherein each of said tendon supports has a thread part and a height-adjusting knob so that the height of said tendon support can be adjusted by means of said thread part and said height-adjusting knob. 
   
   
     20. The system as defined in  claim 18 , wherein said tendon base is extended in the 
     lateral direction so that said tendon base does not make contact with said support beams, said second and the third tendon supports being fixed to said supporting members by means of “L”-shaped bolts. 
   
   
     21. The system as defined in  claim 18 , wherein said tendon base is disposed at both sides of said supporting members so that said tendon base does not make contact with said support beams, said second and the third tendon supports being fixed to said supporting members by means of “L”-shaped bolts. 
   
   
     22. The system as defined in  claim 17 , wherein said anchoring units are attached to the upper surfaces of said supporting members, and wherein each of said anchoring units comprises gusset plates disposed between flanges of said supporting members, a tendon support plate attached to one side of said flanges, and an anchoring steel plate and a supporting steel plate connected to said tensioning member. 
   
   
     23. The system as defined in  claim 17 , wherein said anchoring units are attached to the side surfaces of said supporting members, and wherein each of said anchoring units comprises gusset plates disposed between flanges of said supporting members, and a tendon support plate attached to said reinforcing steel plate, said tensioning member being fixed to said tendon support plate. 
   
   
     24. The system as defined in  claim 1 , wherein said supporting members are supported by means of jack supports mounted to a floor slab, said floor slab being a part of the main structure. 
   
   
     25. The system as defined in  claim 1 , wherein “[”-shaped channels are inserted between said flanges of said supporting members for reinforcing said supporting members.